Background: Chronic kidney disease is a major worldwide problem.
Although epidemiologic and experimental studies suggest that
n–3 long-chain polyunsaturated fatty acid (n–3 LCPUFA) supplementation
may prevent or slow the progression of kidney disease,
evidence from clinical trials is inconsistent.
Objective: The objective was to combine evidence from controlled
clinical trials to assess the effect of n–3 LCPUFA supplementation
on the change in urine protein excretion (UPE) and on glomerular
filtration rate (GFR).
Design: We performed a meta-analysis of clinical trials that tested
the effect of n–3 LCPUFA supplementation on UPE, a marker of
kidney damage, and on GFR, a marker of kidney function. A randomeffects
model was used to pool SD effect size (Cohen’s d) across
studies.
Results: Seventeen trials with 626 participants were included in the
meta-analysis. Most trials focused on patients with a single
underlying diagnosis: IgA nephropathy (n ¼ 5), diabetes (n ¼ 7),
or lupus nephritis (n ¼ 1). The dose of n–3 LCPUFAs ranged from
0.7 to 5.1 g/d, and the median follow-up was 9 mo. In the pooled
analysis, there was a greater reduction in UPE in the n–3 LCPUFA
group than in the control group: Cohen’s d for all trials was 20.19
(95% CI: 20.34, 20.04; P ¼ 0.01). In a patient with 1 g UPE/d , this
corresponds to a reduction of 190 mg/d. Effects on GFR were
reported in 12 trials. The decline in GFR was slower in the n–3
LCPUFA group than in the control group, but this effect was not
significant (0.11; 95% CI: 20.07, 0.29; P ¼ 0.24).
Conclusions: In our meta-analysis, use of n–3 LCPUFA supplements
reduced UPE but not the decline in GFR. However, small
numbers of participants in trials, different methods of assessing
proteinuria and GFR, and inconsistent data reporting limit the
strength of these conclusions. Large, high-quality trials with clinical
outcomes are warranted.